Co0.85Se hollow nanospheres anchored on N-doped graphene nanosheets as highly efficient, nonprecious electrocatalyst for hydrogen evolution reaction in both acid and alkaline media

Developing nonprecious electrocatalysts with high efficiency in both acid and alkaline electrolytes is extremely important for realizing scalable water-splitting technology. Herein, for the first time, we present a facile and cost-effective hydrothermal approach to synthesize a novel hybrid electrocatalyst of Co0.85Se/nitrogen-doped graphene, where Co0.85Se hollow nanospheres are homogenously anchored on nitrogen-doped reduced graphene oxide nanosheets. This hybrid electrocatalyst delivers outstanding hydrogen evolution reaction performance with very low onset potentials of -159 and -111 mV, low overpotentials of -209 and -227 mV at 10 mA cm(-2), and small Tafel slopes of 36.1 and 76.5 mV dec(-1) in acid and alkaline electrolytes, respectively. Furthermore, it shows superior durability even after 1500 cycles. The excellent electrocatalytic performance of the Co0.85Se/nitrogen-doped graphene can be attributed to its well-designed nanoarchitecture. By anchoring Co0.85Se hollow nanospheres on highly conductive graphene nanosheets, the aggregation of Co0.85Se nano spheres is well suppressed, thus increasing the specific surface area and producing abundant exposed active sites. In addition, the charge transfer is greatly facilitated. The remarkable catalytic activity, long-term cycling stability and low-cost synthesis make Co0.85Se/nitrogen-doped graphene a desirable non-precious electrocatalyst for hydrogen evolution in both acid and alkaline electrolytes.